According to the standard of optical disc, the unit of the recording data in an optical disc is a Recording Unit Block (RUB). The disc basically includes a Run-in area, a cluster area (for recording data), a Run-out area and a Guard3 area in sequent order. The Run-in and Run-out areas are specific areas allowing the optical disc drive to synchronize data. The cluster area is for recording the user data. The Guard3 area is employed to prevent unrecorded area occurring between two RUBs in a consecutive recording manner. A consecutive data means data, which is consecutively recorded without blank area existing therein. Contrary to the consecutive data, a non-consecutive data means record data with blank area therein, before or after.
Moreover, a data sync pattern exists in the head of the cluster area and after the Run-in area. The data sync pattern is a specific data pattern prior to a cluster area for the optical disc drive to start the decoding of reading, searching the cluster area data or information in an optical disc.
The HD-DVD specifications use similar definitions for the physical structures as Blu-ray Disc. A VFO field is similar to the Run-in area; a data field is similar to the cluster area; a buffer is similar to the Run-out area; a Guard field is similar to the Guard 3 area, respectively. Similarly, the data sync pattern, a specific data pattern also in the head of the data field for the optical disc drive to start the decoding of reading, searching the data or information in the HD-DVD specifications.
Previously, the optical disc drive can obtain the current position indicated by a pickup head from the RUBs such as CD, DVD, but the content of the RUBs may be variable and sometimes even unpredictable track defects of the optical disc will influence the decoding result from the user data. Therefore, the data sync pattern search method according to the prior art, always searches the data sync pattern in the RUBs from the very beginning of the tracks will result to a high fail rate in the search for the data sync pattern.
Furthermore, discs such as CD-RW or other discs are developed earlier, and if a user is going to write (record) data into the optical disc, the only way of writing data is from the very beginning of the Land or Groove tracks in the optical disc in consecutive manner. The intermittent recording or the recording at arbitrary sector of the Land or Groove tracks in the optical disc will never be allowed. Therefore, searching the data sync pattern to determine the cluster area is also performed from the very beginning as a default setting according to prior arts and is to prevent a mis-recognizing the data sync pattern. However, as the AV (audio and video) optical storage media technology progresses to rewritable digital versatile disc in the present day, the mode of recording data is more arbitrary as according to users' demand. Therefore, optical disc intermittent recording or recording at arbitrary sector of the Land or Groove tracks is now available as one option in Blu-Ray or HD-DVD disc. For example, a user can record one minute of music (or any other digital data) by starting from the track near the periphery of the optical disc; there's no need to start recording data from the very beginning of the tracks. Further, when an optical disc has defects on specified tracks, it will be a great benefit for the user to write the data into the good tracks of the optical disc as desired.
However, such intermittent recording or recording at arbitrary tracks in the optical disc may cause problems of failing to search data sync pattern thereby resulting in mis-decoding the cluster area of the data and causing an unstable status of the whole optical disc drive. In a non-consecutively recorded data, a blank area exists prior to the Run-in area and the cluster area of the data, but the data sync pattern searching method according to the prior arts always searches the data sync pattern in the RUBs from the very beginning of the tracks. However, the data sync pattern searching method according to the prior arts can not recognize the blank area well, meanwhile, searching from the very beginning of the track may increase the mis-recognizing rate if the data of intermittent recording or the data of recording at arbitrary tracks some patterns similar to the data sync pattern. The patterns similar to the data sync pattern existing in the tracks may be mis-recognized by the optical disc drive and causes the optical disc drive to fail in searching the data sync pattern. This mis-decoding occurrence causes the optical disc drive to get trapped in a dead loop as the data sync pattern is never to be located in this manner. Therefore, the blank area may cause the optical disc drive to fail in searching the data sync pattern and the following mis-decoding with high rate
Consequentially, there is a need to develop a data search system for searching in a non-consecutive data in an optical disc and method thereof.